A browser may be divided into two parts in architecture, which are kernel and shell. The browser kernel refers to the core part of the browser, which may be divided into to two part: a layout engineer (or Rendering engine) and a JavaScript (JS) engine. The layout engineer mainly takes charge of obtaining content of webpage (including HTML, XML, images and so on), collating information (such as adding cascading style sheets (CSS) and so on), and calculating the display way of webpage, and then outputting the webpage to display or printer. Different browser kernel may lead to different grammar explanation of webpage, thusly the rendering effect may also be different. All the webpage browser, Email client side and other application which need to edit and display network content need kernel. JS engine is used to parse JavaScript language, execute JavaScript language to obtain dynamic effect of the webpage.
There are various kinds of browser kernel. The commonly-seen browser kernel is Trident kernel used by IE browser from Microsoft, Gecko kernel used by Firefox browser, Webkit kernel used by Safari browser from Apple and chrome browser from Google, and Presto kernel used by Opera browser.
The webpage is usually made according to a certain network standard supported by certain kernel. A network standard supported by certain kernel may not be supported well by other kernels (even cannot be supported by other kernels). For example, when the user uses Firefox browser to browse webpage, the browse kernel of the Firefox may support W3C standard well, thus the browser may be used to browse W3C standard webpages, however, if the user would like to browse bank webpages and use the web bank, the Firefox browser may not satisfy the user's requirement. That is because many web banks and on line payment system requires Active X plug-in function, the function may be supported only by Trident kernel of IE browser, thusly the user cannot use network bank when using the Firefox browser.
To make the user have better experience, the browser manufacturer invented a dual kernel browser mode, that is one browser has two kernels.
When the browser is used to browse the webpage, there is a situation that many webpages may firstly pop out two or three advertisement windows, such as skyscraper advertisements which occupies the whole browser window page display area, and then display the webpage body. However, the webpage body also has many banner advertisements, hover advertisements and floating advertisements, and there are also popped-out Active X control and plug-in installation and downloading, run prompt dialogue, Java program requiring to install Java virtual machine and so on, which seriously affects user browsing webpage, and also increases system running burden.